Enlosures and Energy: What s Working

Transcription

1 "Great spirits have always been met with violent opposition from mediocre minds." - Albert Einstein "To achieve results never before accomplished, we must employ methods never before attempted." - Sir Francis Bacon 1 Enlosures and Energy: What s Working Dr John Straube, P.Eng. Dupont Young Professor Associate Professor School of Architecture & Dept Civil Engineering Waterloo, Canada Straube Presentation NY BEC

2 Why Green? Why Energy? Climate Change Energy Security Environmental Damage Good investments Comfort Durability 3 Chevron Energy Ad 2005 John Straube Straube Presentation NY BEC

3 Energy Supply 5 Fossil fuels becoming unreliable Supply? Cheap oil has run out Oil sands and American oil wont help Major oil field in decline Political disruptions Energy increasingly substitutable Oil switch to natural gas Food or fuel Biomass for boilers or ethanol Plug-in cars compete with buildings Climate Change Even Exxon now says it is happening Reducing climate change by Reducing energy=reducing carbon Absorbing carbon Generating C-free energy Easiest, lowest cost: Passive energy savings 6 See Mazria s Building Engineering Group Straube Presentation NY BEC

4 Green Buildings Recognize buildings have an impact Minimize or eliminate: non-renewable resource use non-renewable energy consumption damage to the local and global ecology production of waste and pollutants 7 Good Buildings Are Green 8 No magic material, widget A systems approach is required Trade-offs, compromises of systems Optimal design requires a broad understanding: people and their behavior city planning transportation ecology materials & production building science & technology Straube Presentation NY BEC

5 Energy and Green Current Buildings Energy use is easy to measure Vast majority of damage done by energy consumption during operation Operational energy reduction is key Material choices less significant Nice to choose lower energy lower polluting alternatives 9 Buildings, Energy, Pollution Buildings consume 68% of all electricity Operation of US buildings 560 million tons of CO 2 per year 36% of US total and 9% of global CO 2 production 49% of US total SO 2 10 Straube Presentation NY BEC

6 Building Operational Energy: Growing Rapidly 40% 30% 20% 10% 11 0% Bldgs Industry Transport Energy & Efficiency 12 People want services not energy Warm house, not gas Light, not electricity Hence, efficiency allow us to have our cake and eat it Energy reductions after 73 / 79 California brownouts(2001): 14% cut in 6 months simply by citizen action Economist Straube Presentation NY BEC

7 The new buzz words Net Zero Energy Carbon-neutral LEED xx% below code How about good buildings? How about reducing energy use? How about REAL NUMBERS? Straube Presentation NY BEC

8 Is it Green? Learning to count Depends on answers to: Does it use less non renewable energy to operate? Will it last longer? (less life-cycle resources) Does it use fewer non renewable resources to build? Does it pollute less? Compared to?: Zero (sustainable) Average (move forward, green ) 15 Changing heat flow control Better heat flow control required today and tomorrow More environmental concerns re: energy Comfort standards more demanding Building materials & finishes are more resistant to condensation (& mold) 16 Straube Presentation NY BEC

9 US Technology Commercial may be the Building problem, not Energy the solution Use Commercial Buildings 80 kbtu/sf 60 Series Before to to to to to to to R2 R6 R6 Insulation - History R6 R3 R4 R4 R1.5 R2 18 R5 Straube Presentation NY BEC

10 Technology to reduce energy+pollution 19 Reduce heat loss and gain Insulation Avoid thermal bridges Use good windows Airtight Avoid energy use Efficient appliances and elevators Collect from sun Use daylighting Then, generate renewable energy Strategies Airtight Insulate well Only small thermal bridges Good windows or few of them Guidance U< 0.33, WWR <25% U<0.25, WWR < 50% U<0.20, WWR >50% 20 Straube Presentation NY BEC

11 How to do it 21 We already know how! (energy reduction) e.g. Good enclosure insulation / airtight (1/2) E.g. Compact fluorescents, controls (1/4) E.g. Highly performance windows (1/3) E.g. Efficient HVAC and office equipment (1/2) Future Superwindows, smart appliances Renewable / bio-materials, low embodied energy Building systems that allow recycling How much insulation? Regardless of type, use more For Comfort & moisture control True R7-10 is enough!, but.. For energy and the environment As much as practical & economical Increased insulation should reduce HVAC capital cost as well as operating! Practical constraints often the limit How much space available? 22 Straube Presentation NY BEC

12 R-values Given as equivalent conductance Never intended to account for realities such as: 1. Thermal Bridges 2. Thermal Mass 3. Air Leakage New methods and materials mean R- value often has less meaning 23 It s More Than Insulation! Thermal bridges provide a path for heat around insulation Heat passes through the structural members Common offenders Floor and balcony slabs Shear walls Window frames Steel studs 24 Straube Presentation NY BEC

13 Find the thermal bridge 25 Heat bridging through steel studs 26 Straube Presentation NY BEC

14 Internal Stack Effect Gaps in batt insulation on both sides closed circuit energy cost cold surfaces Cold air = heavy Cold Weather Hot air = light Result: Air Flow 27 Cool Exterior Hot Interior Steel studs provide conduits Gaps in batt insulation on both sides hard to fill steel studs Hot Batt Hot air = light Air gaps Cold air = heavy Cold 28 Straube Presentation NY BEC

15 R-value Comparison w/r11 29 Adding studspace insulation is not helpful! Get R0.6 Get R Add R2 Add R2 Straube Presentation NY BEC

16 Impact of Insulating Sheathing w/r11 31 Thermal Bridge Examples Balcony, etc Exposed slab edge, 32 Straube Presentation NY BEC

17 Thermal Bridging: Common Problems Not Just Energy: Comfort and Condensation/mold 33 Solving Thermal Bridging / Energy Waste Insulate the thermal bridge Exterior insulation solves most thermal bridges Inside insulation: difficult to cover structural penetrations Common Fix Lower interior RH to stop condensation 34 Straube Presentation NY BEC

18 Thermal bridge problem Solution: exterior insulation 35 All on the exterior 36 Straube Presentation NY BEC

19 Windows & Curtainwalls Our most expensive thermal bridges U-value 0.33 = R3 U-value 0.50 = R2 37 Performance Issues and Metrics Heat Flow (R,U) Solar Heat Gain Coefficient (SHGC) Visual Transmittance (VT) Condensation resistance (CRI) Air Leakage Water penetration Impact and Blast 38 Straube Presentation NY BEC

20 Windows, Insulated Enclosures R3 R2 R4 39 High tech? Low tech? High Performance R12 Southwall R8 R6 R24 40 Kawneer Visionwall Straube Presentation NY BEC

21 How much glass? 41 Total Heat Flow Curtain Wall Plan View R2.5 R4 glazing system U-value R4 R12 42 Straube Presentation NY BEC

22 43 PTB 44 Straube Presentation NY BEC

23 Overall U-Value The overall thermal performance of the window depends on Materials (Glazing, Coatings, Fills, Frame) Geometry (Window, Frame) Type of Window (Operable = more air leakage) Installation (Position, Interface with walls) Generic overall U-values are provided in many text & handbooks (e.g. ASHRAE) U-value over 0.5 is bad!!- aim for U <0.33 Most manufacturers publish overall U-values for their products (rated by the NFRC) 45 Low-e Coatings Low-e coatings reduce the amount of heat transferred by radiation Coating Uncoated Glass Low-e 0.2 Low-e 0.1 Low-e 0.03 Emissivity Radiation Reduction - 62% 79% 93% 46 Straube Presentation NY BEC

24 Gas Fills Gas fills reduce the amount of heat transferred by conduction and convection through the space in the glazing unit Fill Conductivity W/mK Conductivity R/inch Reduction in Conduction Air Argon % Krypton % Xenon % 47 Double IGU 48 ¼ ½ ¾ Straube Presentation NY BEC

25 Triple IGU Triple Glazing: Use in cold climate when WWR>50% e.g., when the budget allows this high a window area R9 49 ¼ ½ ¾ Comfort Warmer windows = more comfort! 50 Straube Presentation NY BEC

26 More Frames = More Heat Loss R1.5 R2 R3 Kawneer Isoport Solar Gains - July N 52 Straube Presentation NY BEC

27 Solar Gains - Jan 45 N Mother Nature is try to tell you something 53 Shade 54 Straube Presentation NY BEC

28 Solar Heat Gain Solar gain through glazing dominates cooling capacity installed Solar Heat Gain Coefficient Ratio of solar heat available: penetrates Clear double glass SHGC about 0.70 Spec < 0.50 if small window area Spec <0.30 for larger window area Exterior shades work, interior shades dont 55 Double Facades Controlling solar heat gain by placing building in a green house Reported energy use high Research shows DF are energy pigs Great design is lipstick 56 Straube Presentation NY BEC

29 Levine Hall at U of Penn much higher: almost 3 times a modern office (290 kbtu/sf) 376 kwh/yr = 122 kbtu/sf/yr 57 Strategies: Windows + Curtainwalls High ratios almost always a problem Restrain use, or use very high performance- simple guidance: WWR<0.25, U<0.35, SHGC <0.45 or shade WWR<0.50, U<0.30, SHGC <0.30 or shade WWR>0.50, U<0.25, SHGC<0.20 or shade Bias toward South-facing windows Beware west-facing 58 Straube Presentation NY BEC

30 Solutions: Process Set goals and metrics E.g. Mazria s 2030.org 30, 50% reduction in energy? Carbon? Compare predictions to target Early and often Confirm concept plans can work Apply systems approach Trade-off HVAC, enclosure, finishes, etc Good insulation, airtighten, windows 59 How to do it 60 System integration Professional specialization disease Sub-system optimization Non-optimal whole system design Real benefits come as a system, not individual Airtight, shade and solar windows save AC costs, fans, and ducts Better insulation can mean simple zoning, HVAC Reduced power req ts = alternative energy economical Future Proofing Straube Presentation NY BEC

31 Concept Design Major cost / performance constraints imposed by concept design Anything possible with budget 61 A note on Daylighting Good daylighting lots of glass Glare! overbright Daylighting energy savings unless controls are installed Window to wall ratios of 35-50% are in the optimum range for energy and daylighting More windows = more glare, energy costs, discomfort 62 Straube Presentation NY BEC

32 What about Renewable Energy? "I'd put my money on the sun and solar energy. What a source of power! I hope we don't have to wait 'til oil and coal run out before we tackle that." --Thomas Edison 190? 63 Renewable Energy Renewable Energy is often part of green / low-carbon buildings is almost always more expensive makes no sense if you waste energy Low energy buildings make RE work e.g. 20 > 45 On site production in distributed manner is part of a total solution Balance loads Reduce grids / transmission 64 Straube Presentation NY BEC

33 Green on the Grand Enermodal Engineering 65 much lower energy consumption < 40 kbtu/sf/yr w/high occupant density much lower resource consumption better air quality lower first cost Waterloo Dorset Apartments Below average cost ($125/sf) About 1/3 average energy consumption (33 kbtu/sf) Better durability, quiet, healthy 66 Straube Presentation NY BEC

34 67 NRG Office Building Vermont 68 Cost 2005 about $120/sf Around 25% of standard energy use Approx 20 kbtu/sf/yr Generates 2/3 on-site Building Engineering Andy Shapiro Group - Consultant Straube Presentation NY BEC

35 Summary good targets 69 Airtighten Tested under 2.5 Insulate well R20+ opaque walls Only small thermal bridges Simple shapes (high floor area to enclosure area) Insulated windows, control solar gain, or use few of them, WWR<0.25, U<0.35, SHGC <0.45 or shade WWR<0.50, U<0.30, SHGC <0.30 or shade WWR>0.50, U<0.25, John Straube SHGC<0.20 or Building shade Engineering Group The Future Paradigm shift from least evil to as much good Buildings must eventually Produce energy Clean air and water Enhance local ecology Reuse materials, low-damage recycle, 70 Straube Presentation NY BEC

36 Conclusions Energy control is getting more important Window U-values & R-value are often bogus Thermal bridging Installation Airtightness is critical Visit us on the web at 71 Straube Presentation NY BEC